1. Technical Field
This invention relates to an electron beam system and an electron beam measuring and observing methods for performing three-dimensional measurement or three-dimensional observation of a sample with high precision using images of the sample photographed with an electron microscope.
2. Related Art
In the case of a transmission electron microscope (TEM), the sample is tilted to obtain transmission images at different tilt angles, and stereo observation is performed using the images as right and left images. In the case of a scanning electron microscope (SEM), the sample or the electron beam is tilted to obtain reflection images at different tilt angles, and stereo observation is performed using the images as right and left images as described in Non-Patent Document 1. In the field of semiconductor producing equipment, an electron beam device and a data processing device for an electron beam device are proposed which are capable of appropriately processing stereo detection data obtained from an electron microscope to permit precise three-dimensional observation of an image of a sample and performing three-dimensional shape measurement of the sample based on the observation as disclosed in Patent Documents 1 and 2.
In measuring a sample such as a semiconductor chip or a silicone wafer, however, electron beam distortion or magnification distortion derived from the tilt angle and height of the sample is involved. When electron beam distortion or magnification distortion in the direction in which the sample image is measured is involved, the accuracy in performing image measurement of the sample varies. In fine processing of semiconductor in recent years, the width of the patterns formed on a chip is as small as in the order of submicron, and the margin of dimensional error acceptable in three-dimensional shape measurement is extremely small as compared in the past.
When a measuring object is photographed with a microscope, it is preferred to photograph an area of it where a failure is likely to occur in semiconductor fine processing or to photograph it from an angle suitable for production process management. However, when a measuring object is photographed from many angles, it takes long to complete the photographing and the throughput of semiconductor fine processing is decreased. If an image of a measuring object photographed in an attitude can be converted into an image in a standard attitude suitable for product management and process control and if the image processing for the conversion takes shorter time than photographing the measuring object from many angles, the throughput of semiconductor fine processing is not decreased.
This invention is made to solve the above problem, and it is, therefore, an object of this invention to provide an electron beam system and an electron beam measuring and observing methods by which three-dimensional measurement and observation of a sample can be performed with high precision irrespective of the tilt angle or the height of the sample.
Another object of this invention is to provide an electron beam system and an electron beam measuring method by which three-dimensional measurement of a sample can be performed with high precision irrespective of the tilt angle or the height of the sample and by which an image of a sample photographed in an attitude can be converted into an image photographed in another attitude suitable for the purpose of use.